Magnetic reed relay



Aug. 23, 1966 MQ L 3,268,839

MAGNETIC REED RELAY Filed March 5, 1965 2 Sheets-Sheet 2 FIG.5

FIG.6

INVENTOR.

GEORGE L. MCFARLAND known United States Patent 3,268,839 MAGNETIC REED RELAY George L. McFarland, Salem, Va., assignor to General Electric Company, a corporation of New York Filed Mar. 5, 1965, Ser. No. 437,531 1 Claim. (Cl. 335-151) This invention is directed to a reed relay, and more particularly to a reed relay which has increased efficiency and is little affected by extraneous magnetic fields.

Reed relays are well known in the electronic art and find extensive use. The reed relay consists of a reed switch and a coil. The reed switch has two reeds made of a magnetic material and positioned so that normally they do not touch each other. The two reeds are hermetically sealed in a capsule, normally of glass, with the reeds extended through the capsule toconnect with terminal leads. The coil is positioned around the capsule with the reeds therein so that when the coil is energized, the two reeds are magnetized and closed to complete a circuit through the reed switch.

A plurality of these reed switches are often used together such as in scanning systems and are located physically close together on the circuit board. The m-agnetic field of one reed relay will at times affect a neighboring reed relay. Since the magnetic field tends to stray in this manner, a comparatively large pick-up coil is required to close the two reeds. If there are a number of neighboring reed relays, the combined magnetic fields may affect the drop-out characteristics.

It is therefore an object of this invention to provide a new and improved reed relay which will not affect nor be afiected by neighboring reed relays. Another object of this invention is to provide a new and improved reed relay which is more efficient than previous reed relays.

According to this invention, therefore, a reed switch having two reeds of magnetic material is inserted in a magnetic coil. The reed switch and the magnetic coil is then enclosed in an enclosure of magnetic material. The magnetic enclosure becomes the return path for th magnetic flux of the magnetic field from the coil.

The invention is set forth with particularity in the appended claim. The principles and characteristics of the invention, as well as other objects and advantages are revealed and discussed through the medium of the illustrative embodiments appearing in the specification and drawing which follow.

In the drawing:

FIG. 1 is a crosssectional view of a magnetic reed relay constructed according to this invention.

FIG. 2 shows one end cap of the reed relay.

FIG. 3 is a view of the top portion of the enclosure of the reed relay.

FIG. 4 shows the bottom portion of the enclosure for the reed relay.

FIG. 5 is a view of the other end cap of the reed relay.

FIG. 6 is a diagrammatic representation of the magnetic field from the magnetic coil of the reed relay.

FIG. 7 shows a cut-away view of an electrically actuated reed switch, encased in a cold-rolled steel shielding enclosure.

Referring to FIG. 1, the reed switch 11 is surrounded by the coil bobbin 13, which supports coil 15. At one end the coil bobbin 13 is supported by the end cap 17.

FIG. 2 shows an inside view of end cap 17. From a central recessed area 27, four slots 19-22 radiate diagonally outward. One of these slots 19-22 wil-l allow the passage of connection lead 29 around the coil bobbin 13 as shown in FIG. 1.

The end cap 33, shown in FIGS. 1 and 5, is similar to the end cap 17 except there is a through opening 35 in the end cap 36 as opposed to a recessed area 27 in the 3,268,339 Patented August 23, 1966 end cap 17. The four slots 7 1-74 and opening 35 shown in FIG. 5 allow the passage of coil leads 37 and 39 and the main contact leads 29 and 41 (FIG. 1). FIG. 1 shows that end cap 33 and end cap 17 are held together by a steel cover 43 and a base 45. Both cover 43 and,

base 45 are equipped with small flanges 47, 49, 51, and 53 shown in FIGS. 1, 3 and 4 which prevent the end cap 17 and the coil support 33 from sliding outward.

The cover 43 as shown in FIG. 3 is a U-shaped steel assembly with several extensions 55-58 along edge 63 of the open side of the U. Edge 69 has corresponding protrusion-s of which only 65 and 66 are visible in FIG. 3.

The base 45 is a flat steel assembly with two flanges 49 and 5-1 at each end as shown in FIG. 4. A

The magnetic reed switch 11 is a reed switch of the conventional type widely used. Such magnetic reed switches are hermetically sealed in a capsule of a nonmagnetic material' such as glass.

Within the capsule 79 are two reeds 81 and 83 made 'of magnetic material. The reeds are plated with any suitable contact metal and extend through the capsule to connect with the main contact terminals 31 and 69.

The reeds are positioned so that they do not touch each other until they are magnetized by coil 15.

The coil 15 consists of length of insulated copper wire of suitable diameter wound around the coil bobbin 13. The end and the beginning of this wire are connected to the leads 37 and 39.

The coil bobbin 13, the end cap 17, and the end cap '33 are fabricated from a plastic material.

By modifying the coil bobbin 13 a plurality of reed switches may be operated from one coil. The complete assembly would become larger depending on the number of reed switches which were to be operated.

Leads 29 and 41 are soldered to the main pole contact terminals 31 and 69 of reed switch 11. Reed switch 11 is then inserted into the coil bobbin 13. The lead 29 is folded back over coil 1'5.

End cap 17 is now pushed over the main contact terminal until the recess 27 engages with the end of the coil bobbin 1 3. The lead 29 is adjusted so that it passes through one of the slots 19-22 (FIGS. 1 and 2) thus clearing coil bobbin 13.

All of the leads 29, 37, 39 and 41 are now passed through opening 35 in coil holder 33. End cap 33 is now pressed over the contact terminal 69 of reed switch 11 until it engages with coil bobbin 1 3 in a manner similar to the end cap 17.

The leads 29, 37, 39 and 41 are guided through slots 71-04 (FIGS. 1 and 5) in the end cap 33 thus clearing coil bobbin 13.

The cover 43 is now placed over the assembly of coil 15, reed switch 1 1, end cap 17 and end cap 33 in such a manner that flanges 47 and 53 will retain the end cap 17 and end cap 3 3.

The base 45 is now applied to the bottom of the coil '15, end cap 17 and end cap 33. Flanges 49 and 51 will retain end cap 17 and end cap 33.

Now the extensions 56, 57, and 66 of cover 43 are now folded under the base 45, thus forming a complete shield ing enclosure around the reed relay.

A sealant such as room temperature vulcanizer, R.T.V., or equivalent, is used to seal the opening 35 in end cap 33. This anchors the leads 29, 37, 39, 41 and contact terminal 69 permanently.

As coil 15 becomes energized, a magnetic field is created as represented by the dashed lines in FIG. 6. Since the cold-rolled steel used for the cover 43 and the base 45 is a better conductor of magnetism than air, the cover 43 and the base 45 become the return path for the magnetic flux.

The eifect is increased efliciency within the relay itself and an elimination of the efiect by magnetic fields from neighboring relays.

The magnetic flux is confined to the enclosure and does not affect neighboring relays. The effect of the magnetic field is not dissipated in the air but limited to within the enclosure so that the relay becomes more efiicient.

In summary, a new and improved magnetic reed relay has been described. The reed relay is enclosed in an enclosure of magnetic material so that the magnetic flux returns through the enclosure rather than in the air. In this manner the magnetic field does not aifect and is not affected by neighboring reed relays and the efiiciency of the reed relay is increased.

While the invention has been explained and described with the aid of particular embodiments thereof, it will be understood that the invention is not limited thereby and that many modifications retaining and utilizing the spirit thereof without departing essentially therefrom will occur to those skilled in'the art in applying the invention to specific opera-ting environments and conditions. It is therefore contemplated by the appended claim to cover all such modifications as fall within the scope and spirit of the invention.

What is claimed is:

-A magnetic reed relay comprising, a reed switch having two reeds of a magnetic material normally positioned so that they do not touch each other, leads connected to both ends of said reed relay, a bobbin of a plastic material positioned around said reed switch, a magnetic coil wound on said bobbin to close said two reed switches when the coil is energized, a closed end cap supporting one end of said bobbin adapted to engage one end of said reed relay, said closed end cap having a plurality of radial slots adapted to pass the lead connected to that end of said reed relay, an open end cap supporting one end of said bobbin adapted to engage one end of said reed relay, said open end cap having a plurality of radial slots adapted to pass the leads of said reed relay, and an enclosure of a magnetic material enclosing said end caps and said bobbin to provide a return path for the magnetic flux of said magnetic coil.

References Cited by the Examiner UNITED STATES PATENTS 2,903,536 9/1959 McBrian 200-87 2,978,556 4/1961 Lohs et al. 20087 3,138,679 6/1964 Lawrence 20087 3,171,918 2/1965 Killion 20087 3,174,008 3/ 1965 Mishelevich 20087 3,196,232. 7/1965 Lisuzzo et a1. 20087 BERNARD A. GILHEANY, Primary Examiner.

B. DOBECK, J. BAKER, Assistant Examiners. 

